Strangers can have more intimate conversation, while travelling.

I was searching for the word "conversation" in the internet and I read in the world's biggest encyclopedia that strangers can have more intimate conversation while traveling, which they don't have in other normal situations.
For example people have intimate conversations while traveling through buses, chances are more if one is mental health professional and the other is looking for help in the personal relationships.
I also think that it is true from my past experiences. what ideas do you share about this topic?